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MoonWalker
29th September 2002, 22:24
Is there anyway to calculate if there is a scene change in one frame from the 1-pass stats file variables??

Thanks,
MoonWalker
NiTroGen
1st October 2002, 14:08
Well, if there are only keyblocks in a frame and it is not a keyframe, then surely there is a scene change.
Koepi
1st October 2002, 17:20
This should be impossible to happen: if more than 50% of the blocks are intra-blocks (hardcoded value), an intra-frame (keyframe) is inserted instead an interframe.

Regards,
Koepi
NiTroGen
1st October 2002, 17:39
Originally posted by NiTroGen
Well, if there are only keyblocks in a frame and it is not a keyframe, then surely there is a scene change.
That was how a scene change was identified before the codecs with a scene changing detection routine (eg. DivX 3.11, MS-MPEG4, etc).
Since XviD identifies scene changes and inserts a keyframe, the only way to identify a scene change is to know the maximum keyframe interval of the encoded video and see the distance between keyframes. If is lower than the interval then there "should be" a scene change. But if you don't know the interval, then a not-very-accurate way to guess it is to analyse all the keyframe distances. The maximum one "could be" the interval. (I hope Koepi agrees with me)

Btw, MoonWalker, why do you want to find the scene changes?
Defiler
2nd October 2002, 16:20
I'd imagine that he wants XviD Analyzer to report scene changes. I can imagine that being helpful when cutting AVI files into multiple parts. How close am I, Moonwalker?
MoonWalker
2nd October 2002, 17:51
Originally posted by Defiler
I'd imagine that he wants XviD Analyzer to report scene changes. I can imagine that being helpful when cutting AVI files into multiple parts. How close am I, Moonwalker?

Hmm...I haven't thought that way ;)...I want to compare the 1-pass keyf-frame distribution(inluding the scene changes) to the 2-pass key-frame distrubution to see where the key-frames are removed(cause I have only saw removal of key-frames on the 2-pass)..BTW I have tested with xda (with a little change ;) ) the 1-pass stats file for CC key-frames and I didn't find any...

MoonWalker